The hypothesis of Andreas Cellarius, showing the planetary motions in eccentric and epicyclical orbits.
The tectonic plates of the world were mapped in the second half of the 20th century. Plate tectonic theory successfully explains numerous observations about the Earth, including the distribution of earthquakes, mountains, continents, and oceans.
The first observation of cells, by Robert Hooke, using an early microscope. This led to the development of cell theory.
In quantum mechanics, the electrons of an atom occupy orbitals around the nucleus. This image shows the orbitals of a hydrogen atom (s, p, d) at three different energy levels (1, 2, 3). Brighter areas correspond to higher probability density.
Precession of the perihelion of Mercury (exaggerated). The deviation in Mercury's position from the Newtonian prediction is about 43 arc-seconds (about two-thirds of 1/60 of a degree) per century.

Even though the words "hypothesis" and "theory" are often used interchangeably, a scientific hypothesis is not the same as a scientific theory.

- Hypothesis

The scientific method involves the proposal and testing of hypotheses, by deriving predictions from the hypotheses about the results of future experiments, then performing those experiments to see whether the predictions are valid.

- Scientific theory
The hypothesis of Andreas Cellarius, showing the planetary motions in eccentric and epicyclical orbits.

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Alpha

The scientific method is often represented as an ongoing process. This diagram represents one variant, and there are many others.

Scientific method

Empirical method of acquiring knowledge that has characterized the development of science since at least the 17th century .

Empirical method of acquiring knowledge that has characterized the development of science since at least the 17th century .

The scientific method is often represented as an ongoing process. This diagram represents one variant, and there are many others.
Precession of the perihelion – exaggerated in the case of Mercury, but observed in the case of S2's apsidal precession around Sagittarius A*
Einstein's prediction (1907): Light bends in a gravitational field
Model of DNA with David Deutsch, proponent of invariant scientific explanations (2009)

It involves formulating hypotheses, via induction, based on such observations; experimental and measurement-based testing of deductions drawn from the hypotheses; and refinement (or elimination) of the hypotheses based on the experimental findings.

The most successful explanations – those which explain and make accurate predictions in a wide range of circumstances – are often called scientific theories.

Here are two black swans, but even with no black swans to possibly falsify it, "All swans are white" would still be shown falsifiable by "Here is a black swan"—a black swan would still be a state of affairs, only an imaginary one.

Falsifiability

Standard of evaluation of scientific theories and hypotheses that was introduced by the philosopher of science Karl Popper in his book The Logic of Scientific Discovery .

Standard of evaluation of scientific theories and hypotheses that was introduced by the philosopher of science Karl Popper in his book The Logic of Scientific Discovery .

Here are two black swans, but even with no black swans to possibly falsify it, "All swans are white" would still be shown falsifiable by "Here is a black swan"—a black swan would still be a state of affairs, only an imaginary one.
A black-bodied and white-bodied peppered moth
Clyde Cowan conducting the neutrino experiment (c. 1956)

A theory or hypothesis is falsifiable (or refutable) if it can be logically contradicted by an empirical test that can potentially be executed with existing technologies.

Even very young children perform rudimentary experiments to learn about the world and how things work.

Experiment

Even very young children perform rudimentary experiments to learn about the world and how things work.
The black box model for observation (input and output are observables). When there are a feedback with some observer's control, as illustrated, the observation is also an experiment.

An experiment is a procedure carried out to support or refute a hypothesis, or determine the efficacy or likelihood of something previously untried.

Researchers also use experimentation to test existing theories or new hypotheses to support or disprove them.

The Old Farmer's Almanac is famous in the US for its (not necessarily accurate) long-range weather predictions.

Prediction

Statement about a future event or data.

Statement about a future event or data.

The Old Farmer's Almanac is famous in the US for its (not necessarily accurate) long-range weather predictions.
Prediction market.
Approval ratings (percentages) for the 2004 Canadian federal election

In a non-statistical sense, the term "prediction" is often used to refer to an informed guess or opinion.

A scientific theory whose predictions are contradicted by observations and evidence will be rejected.